Bone disorders such as osteomyelitis (OM) that result from bacterial infection are associated with severe inflammation and progressive bone loss. Staphylococcus aureus, is the most common causative agent of OM and the incidence and severity of staphylococcal OM appears to be increasing despite improvements in prophylaxis and diagnosis. Dysregulation of osteoclast (OC) formation and activity results in bone destruction and/or abnormal bone remodeling at sites of infection, and osteoblasts (OBs) play an essential role in the regulation of these bone-resorbing cells. In addition, bacterially infected OBs are capable of producing an array of immune mediators that could promote the recruitment and activation of inflammatory leukocytes in bone tissue. The neuropeptide substance P (SP) is increasingly recognized to exacerbate inflammation in a range of tissues including the gut, skin, airways and CNS. Given the extensive innervation of bone tissue with SP-containing nerve fibers, the functional expression of the specific receptor for SP (NK-1R) by bone cells, and previous evidence that this neuropeptide can modulate bone cell responses, we suggest that SP/NK-1R interactions exacerbate inflammation in OM. In this Academic Research Enhancement Award (AREA) R15 application, we propose an initial preclinical evaluation of the ability of this neuropeptide to augment inflammation in isolated primary resident bone cells and an established in vivo animal model of staphylococcal OM. This work builds upon our prior work and will test the hypothesis that inhibition of SP/NK-1R interactions attenuates the immune and osteolytic responses of resident bone cells to bacteria. This R15 project offers tremendous opportunities for hands-on laboratory research experience by both undergraduate and graduate students in the biological sciences at our institution, and represents an essential first step in evaluating the therapeutic potential of repurposing NK-1R antagonists as an adjunctive therapy to limit staphylococcal OM associated inflammatory bone loss and/or abnormal bone remodeling. !